This is one of a fair few I did when calibrating ... errrr I the 60mm I think

Again, because the array's have a horizontal and vertical component (worse in D7000 due to array size)...setting your AF-Fine tune based on angled targets (especial close range) can result in an inherent error. May not show up when you "check" using a flat wall and CDAF vs PDAF comparison due to DoF limitations. Will show up though (if the setting was off) when shooting at different distances at subject occupying a tiny field of focus.

Example: This is is a perfectly calibrated 50mm lens (requires zero adjustment). Focused here on the center dark line. Had I used these results to set AF-Fine tune...I would have induced an error and set a - correction when none was actually required.

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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)